Common practice for well casings?

[gndrod]

EGC...

EGC...

The well casing may be an electrode but around here the well is often 100+ feet from the home. Does the gec being run that distance change the effectiveness of the electrode itself?

Your question should not be about the GEC. Please read posts #3 and @#18 carefully....

 

[iwire]

Your question should not be about the GEC. Please read posts #3 and @#18 carefully....

Dennis and I were discussing using the casing as an electrode.

 

[gndrod]

Dennis and I were discussing using the casing as an electrode.

I realize that, but at a hundred feet away for a well motor system from a main disconnect, that becomes irrelevant in the case electrode-to- soil impedance effectivity.

 

[Dennis Alwon]

I realize that, but at a hundred feet away for a well motor system from a main disconnect, that becomes irrelevant in the case electrode-to- soil impedance effectivity.

I am confused. I thought we were talking about the fact that it probably would not be effective as an electrode at that distance. :?

 

[gndrod]

I am confused. I thought we were talking about the fact that it probably would not be effective as an electrode at that distance. :?

Hi Dennis,

PAX. If Bob's dialog was in reference to a casing not being effective as an electrode I do agree and must have missed it. I guess I was too focused on answering the OP's initial question with the reason why requiring an EGC bonding is imperative for well metal casing equipment safety.

 

[George Stolz]

On a practicality note, using a metal casing is no longer common for modern well installs for both handling, water purity and electrolysis reasons that this discussion does not entail.

Metal well casings are still common in my area.

 

[gndrod]

Metal well casings are still common in my area.

Hi George,

Interesting....for deep submersible water? Is there a reason for using the metal? For agri? Mining including gas?

 

[kwired]

Metal well casings are still common in my area.

Are they metal for the full depth of well?

There are old metal wells here also.

New ones for at least 25-30 years are usually non metallic. The last few feet, and/or 'pitless adapters' will usually be steel to stand up to physical abuse above grade. I live in "irrigation country" and there are a lot of wells from 4 inch to 12 inch casings everywhere.

 

[George Stolz]

Hi George,

Interesting....for deep submersible water? Is there a reason for using the metal? For agri? Mining including gas?

For residential-use submersible pumps. No idea, no idea, no idea.

Are they metal for the full depth of well?

Not typically, but I know of one well driller that does. I think mine goes down 20 or 30' to prevent surface water from entering the well, I think.

I'd post a picture of mine, but it's under snow at the moment.

 

[realolman]

Why would a ground rod be required to be connected with a #6 , but a well casing (which I believe would be a far superior ground rod ) only be required to be connected with a # 12 if the pump had a 20 a OCPD?

I could understand anything likely to become energized to have a EGC appropriate to the size of the OCPD, but I don't think a well casing is an ordinary " likely to become energized" ... I think it is more of a grounding electrode.

 

[kwired]

For residential-use submersible pumps. No idea, no idea, no idea.


Not typically, but I know of one well driller that does. I think mine goes down 20 or 30' to prevent surface water from entering the well, I think.

I'd post a picture of mine, but it's under snow at the moment.

The only way to keep surface water out is to slope grade away from the well. Metal or plastic, unless there is a failure water only enters in the locations where casing intentionally has holes or "screen" to allow water in. Surface water if not drained away from well will percolate down into the supply that feeds the well, but has nothing to do with whether or not a metallic or non metallic casing is used.

 

[Dennis Alwon]

Why would a ground rod be required to be connected with a #6 , but a well casing (which I believe would be a far superior ground rod ) only be required to be connected with a # 12 if the pump had a 20 a OCPD?

I could understand anything likely to become energized to have a EGC appropriate to the size of the OCPD, but I don't think a well casing is an ordinary " likely to become energized" ... I think it is more of a grounding electrode.

In one case you are using the ground rod as an electrode in the situation of the well case you are just bonding the casing and not using it as an electrode. In the event that it is used as an electrode then I believe you would need to follow 250.66.

 

[chris1971]

Do you guys usually bond well casings with whatever equipment ground you run out there? I don't think there's an actual code reference for this- AHJ? I've been looping the equipment ground (#10 or #12 CU solid from the UF cable) out of a drilled hole in the PVC LB and drill/tap a lay-in lug in the well casing for it. I saw someone actually run a dedicated #4 out there just for the well casing (in addition to the equipment ground), I thought, you must be joking.

We do because it's required and the AHJ looks for it during the final inspection.

 

[gndrod]

For residential-use submersible pumps. No idea, no idea, no idea.


Not typically, but I know of one well driller that does. I think mine goes down 20 or 30' to prevent surface water from entering the well, I think.

I'd post a picture of mine, but it's under snow at the moment.

George,

Thanks for the input. Until the advent of PVC for well casing, thousands of existing metal wells throughout the US were dominant. In the many years of wiring well systems (as far back as 1973), I have had the experience of rewiring old steel or CI wells for safety bonding. All new wells I have set pumps in are PVC, and as a main point in this discussion, does not exempt the well equipment or metal casing from not having bonding with an EGC.
A good reference source is the National Driller and the NGWA.org (National Ground Water Association) for various drilling conditions that dictate steel or PVC.

From an economical and practical view, Google up 'well drilling casing' and click on Steel or PVC for a good pdf explanation.

 

[gndrod]

Are they metal for the full depth of well?

There are old metal wells here also.

New ones for at least 25-30 years are usually non metallic. The last few feet, and/or 'pitless adapters' will usually be steel to stand up to physical abuse above grade. I live in "irrigation country" and there are a lot of wells from 4 inch to 12 inch casings everywhere.

Good point about pitless adapters especially in your area. For systems in the high country adapters are used for frostline conditions.

 

[George Stolz]

I think it is more of a grounding electrode.

By the NEC, it's not unless you decide to use it as such. Do you agree with that statement?

Think of the impedance created by the #12 that is only accessible to the lightning by way of the feeder EGC, to the branch circuit EGC, out an average 150' of overall wire length to get to the casing.

1. You think lightning is going to prefer that path over the rod?

2. Can you imagine the collateral damage throughout the home to all the other paths that are equally attractive?

In one case you are using the ground rod as an electrode in the situation of the well case you are just bonding the casing and not using it as an electrode. In the event that it is used as an electrode then I believe you would need to follow 250.66.

Agreed.

 

[gndrod]

Why would a ground rod be required to be connected with a #6 , but a well casing (which I believe would be a far superior ground rod ) only be required to be connected with a # 12 if the pump had a 20 a OCPD?

I could understand anything likely to become energized to have a EGC appropriate to the size of the OCPD, but I don't think a well casing is an ordinary " likely to become energized" ... I think it is more of a grounding electrode.

I see it is a matter of experience in getting zapped on an old steel well system that has a case fault. The casing is not so superior as a ground rod in that instance. Please refer back to the post #17 to understand the reason for the EGC bonding.

 

[gndrod]

I was going to bring that up.

I believe BPHGravity has pointed out that at the frequency lightning operates at that a typical copper conductor adds a lot of impedance.

I believe he also pointed out that only the first couple of feet of a grounding rod is effective for lightning.

Dear Bob and Dennis,
My apologies for reading past this...now I see what you were saying.

 

[realolman]

OK maybe we can take this one thing at a time.

Unless you do this for a living and have good reason to deviate from an EGC, the questions asked are understandable. In some instances the well casing, under code within a structure would require a grounding electrode.

you're saying that there should be a ground rod to ground the well casing?

 

[gndrod]

OK maybe we can take this one thing at a time.




you're saying that there should be a ground rod to ground the well casing?

If you own a copy of the NEC....try [250.53(A)(2)] (well casing as a pipe or rod electrode) the H2O pipe shall be supplemented. Exc. 25 ohm compliance in this instance.
An EGC bonding for a well casing is what was originally referred to for the OP's question and your wanting to understand why the casing is not a superior ground electrode in true code terms.